1. Field of the Invention
The present invention generally relates to orthopedic implants and, more particularly, to a resurfacing implant for the radioscaphoid joint.
2. Description of Related Art
Osteoarthritis (OA), also known as degenerative arthritis, is a type of arthritis caused by the breakdown and eventual loss of articular cartilage. Cartilage normally serves as a “cushion” between the bones of a joint. Loss of this cartilage cushion causes friction between bones, leading to pain and limitation of joint mobility. OA is the most common form of arthritis and affects over 20 million people in the United States. It commonly affects the hands as well as large weight-bearing joints, such as the hips and knees. The most common type of OA at the wrist joint is periscaphoid OA. This is OA between the proximal scaphoid and the scaphoid fossa of the radius.
Periscaphoid OA can be primary or secondary. Primary OA is usually related to the wear and tear associated with aging. Secondary OA is usually due either to a) injury to the scaphoid bone or b) injury to the scapholunate ligament which attaches the scaphoid to the lunate. The most common symptom of OA is pain at the affected joint. In severe OA, complete loss of cartilage causes friction between bones, leading to pain with motion and at rest. Eventually patients also lose mobility at the affected joint.
Various treatments are currently available for treating periscaphoid OA. One option for treatment is surgery to repair the wrist joint. Such surgical treatments are generally reserved for those patients with OA that are particularly severe and unresponsive to conservative treatments. The two most common surgical treatments for periscaphoid OA are 4-corner fusion (4-CF) and proximal row carpectomy (PRC). Unfortunately both of these procedures lead to loss of wrist motion. Another surgical option is a total wrist fusion. However, a total wrist fusion leads to a complete loss of wrist motion.
Alternative treatment options include wrist arthroplasty or joint replacement. However, current wrist arthroplasty technology has significant limitations. Current total joint replacement implants for the wrist require removing large sections of bone and soft tissues due to the large size of the implants. Current implants also require bone purchase or bone cement for stability. Further, implantation of current wrist implants requires making large incisions in the patient to provide the surgeon with the access required to ensure proper alignment of the implants.
Consequently, patients can experience long operating room times, lengthy recovery, and reduced mobility. Revision surgeries are challenging because substantial bone has been removed, and there may not be a salvage procedure other than fusion of the joint. Partial wrist replacements are available; however, such techniques still require bone removal and lead to soft tissue damage during surgery, leading to joint instability and few revision options.
Accordingly, attempts have been made to develop devices to resurface the distal radius of the wrist. For instance, United States Patent Application Publication No. 2007/0185582 to Palmer et al. discloses a radial implant (100A) for the radius (1) of the wrist. The radial implant (100A) has tapered edges to prevent sharp contact with soft tissue and an articulating surface (102A). The articulating surface (102A) has at least one generally concave surface facing the joint space (5), and can have one or more points of concavity generally shaped and oriented to match the scaphoid bone (2) and the lunate bone (3). The radial implant (100A) also includes a static surface (101A) configured to contact the cartilage, bone, or tissue of the radius (1), and is shaped to generally fit within the radius (1). A stabilizing fin (150A) may also be provided, and can be a fixed component of the radial implant (100A) or a separate attachment connected during assembly of the implant (100A). However, such resurfacing implants still suffer from various deficiencies. Since these resurfacing implants are provided as a single integral piece, a relatively large incision still needs to be made for implantation. In addition, such implants also require the resurfacing of the entire distal radius, even if a portion of the distal radius is still healthy.
Accordingly, a need exists for a resurfacing implant for treatment of periscaphoid OA that is provided in two or more modular components. In addition, a further need exists for a resurfacing implant for the wrist that would resurface the scaphoid fossa of the radius while leaving the lunate fossa of the radius, the distal radioulnar joint, and the ulnocarpal joint intact.